I have a question, and I think the answer will clear up a lot aobut subroutines for me. I am writing a program that asks for a simple addition problem, stores the integers for the addition problem in variables, converts them to words, and displays the problem and the answer in word form. I call the same subroutine for the second integer as I do for the sum, but the subroutine only works for first integer. It doesn't return anything for the sum. Can anybody tell me why? 
#!/usr/bin/perl -w
use strict ;
my (@a, $userin, $userin2, $sum) ;
@a = (1 .. 9) ;
print "This program will ask you to type in two numbers and then add t
+hose numbers together.\nIt will then display the problem and the answ
+er in word form.\n" ;
$userin = 0 ;
while ($userin ne "done") {
    print "Type in a single digit number between one and four, or type
+ done to exit.\n" ;
    chomp ($userin = <STDIN>) ;
    if ($userin eq "done") {
        last ;
    }
    print "Type in a single digit number between one and five\n" ;
    chomp ($userin2 = <STDIN>) ;
    if (($userin =~ /^[^1-4]$/) || ($userin2 =~ /^[^1-5]$/)) {
        print "I do not understand\n" ;
    }
    else {
        $sum = ($userin + $userin2) ;
        $userin = (firstnumtoword($userin)) ;
        $userin2 = (numtoword($userin2)) ;
        $sum = (numtoword($sum)) ;
        print "$userin plus $userin2 equals $sum\n" ;

    }
}

sub numtoword {
    $_ = shift ;
    my (%nums) ;
    %nums = ("1"=>"one", "2"=>"two", "3"=>"three", "4"=>"four", "5"=>"
+five", "6"=>"six", "7"=>"seven", "8"=>"eight", "9"=>"nine") ;
    return $nums{$userin2} ;
}
sub firstnumtoword {
    $_ = shift ;
    my (%nums2) ;
    %nums2 = ("1"=>"One", "2"=>"Two", "3"=>"Three", "4"=>"Four", "5"=>
+"Five", "6"=>"Six", "7"=>"Seven", "8"=>"Eight", "9"=>"Nine") ;
    return $nums2{$userin2} ;
}

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In reply to Subroutine Question by Socrates440

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